[petsc-dev] circular dependencies SLEPc

[Matthew Knepley]

On Mon, Jul 8, 2019 at 10:37 PM Jed Brown via petsc-dev <
petsc-dev at mcs.anl.gov> wrote:

> "Smith, Barry F. via petsc-dev" <petsc-dev at mcs.anl.gov> writes:
>
> >> On Jul 8, 2019, at 9:53 PM, Jakub Kruzik via petsc-dev <
> petsc-dev at mcs.anl.gov> wrote:
> >>
> >> Just to clarify, the suggested solution is a plug-in sitting anywhere
> in the PETSc source tree with postponed compilation and using
> __attribute__((constructor)) to register (as in libCEED) for static
> libraries?
> >
> >   Yes, this is my understanding. Good luck.
>
> There is some nontrivial infrastructure that would be needed for this
> model.
>
> 1. This new component needs to be built into a new library such as
>    libpetsc-plugin.a (when static).
>
> 2. Users need to know when they should link this module.  They'll need a
>    link line something like -lpetsc-plugin -lslepc -lpetsc in this case.
>    It would need to be specified correctly in makefiles and pkg-config.
>
> 3. Anything with __attribute__((constructor)) runs *before* main, thus
>    before PetscInitialize.  There would need to be a new mechanism to
>    register a callback to be run at the end of PetscInitialize.
>

I think the simpler course it just to declare that this does not work
outside of dynamic linking.
The number of platforms that do not have dynamic linking is small, and we
are not putting
anything critical here. This decision can be reevaluated, but for now it
makes everything much
much simpler.

   Matt

-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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